"Not another step!"

HALT

Think of a military command that means to stop moving immediately, often used during drills or inspections.

The clue "Not another step!" is a direct command meaning to stop immediately, which is exactly what "halt" means. There’s no hidden wordplay here—it’s a straightforward definition where the phrase itself is a clear instruction to cease moving. In military or authoritative contexts, "halt" is often used as a sharp order to freeze in place, making it a perfect fit. The exclamation mark even reinforces the urgency of the command.